Triplett LT75 User Manual

User Manual

LT75

Lux/Fc Light Meter

Introduction

Thank you for selecting the Triplett LT75 LUX/FC Light Meter. The LT75
measures light from fluorescent, metal halide, high-pressure sodium and
incandescent sources in lux and foot-candles.

Safety

Please read the entire User Manual before operating this device. Use the
meter only as specified and do not attempt to service or open the meter
housing.

Do not use the meter in the presence of explosive gas or vapor
Do not expose the meter to extremes in temperature or to high humidity

Please dispose of batteries and meter responsibly and in accordance
with all applicable laws and regulations

Do not allow children to handle the meter or the protective cover

Meter and LCD Description

METER DESCRIPTION

1. Light Sensor (protective sensor cover not shown)

2. LCD

3. LUX-FC button

4. Power Button

5. CAL-ZERO
button

6. Data Hold button

7. MAX-MIN Record button
Note: Battery compartment

and Tripod mount on rear
of meter

LCD DESCRIPTION

1. Battery status

2. Auto Power OFF (APO)

3. Data Hold

4. Maximum reading

5. Average reading

6. Minimum reading

7. Measurement

8. Units of measure

9. Calibration (ZERO)

1. Function Indicator

Operation

Meter Power

Power the meter by long pressing the button. The meter will
begin displaying light intensity readings. If the LCD does not switch
on, check the batteries located in the rear battery compartment.
Short press power button to turn OFF the meter.

Zero Calibrate the Sensor

1. Place the protective cover over the sensor and press the

button to power on the meter.

2. If the display does not read ‘0.0’ short press the button.

3. The CAL icon will appear in the secondary display.

4. The CAL icon will switch OFF when the calibration has been

completed.

5. If the protective cap is not covering the sensor when the

button is pressed, the LCD display will read “CAP”. In this case,

please cover the sensor with the cap and restart this procedure.

6. It is recommended that the meter be switched off and then on

again when repeating the zero calibration function.

Taking Measurements

Remove the sensor cover and aim the sensor toward the light source.
View the measurement on the meter’s display.

Selecting the Unit of Measure

Press the button to toggle the units between Lux and Foot­candles. The units will indicate in the display.

Data Hold

Short press the button to freeze or unfreeze a reading on the
display.

MAX/MIN Button

The meter records the maximum, minimum, and average readings as
described below:

1. Short press the button and the meter will begin tracking

the maximum, average, and minimum measurements. The MAX
icon will display at the top of the LCD indicating the meter is
now showing the maximum reading. The reading will not
change until a higher reading is registered.

2. Short press the button again to switch from MAX to AVG,

where the meter will show the average measurement value. The
AVG icon will display in the LCD indicating the meter is now
showing the average reading.

3. Short press the button again to change the mode from AVG

to MIN, where the meter will show the minimum measurement
value. The MIN icon will display in the LCD indicating the meter is
now showing the minimum reading.

4. Short press the button to step through MAX-AVG-MIN

readings.

5. To exit this mode, long press the button. The

MAX/AVG/MIN display icons will switch off, and the meter will
return to normal operating mode.

Auto Power OFF (APO)

In order to conserve battery life, the meter will automatically shut
off after approximately 12 minutes of inactivity. The icon will
appear in the display when APO is enabled.

To turn APO on or off, with the meter powered ON, long press the

button. The icon will appear in the upper LCD when APO is

enabled and disappear when APO is disabled.

Measurement Considerations and User Tips

For maximum accuracy allow the light being measured to fall directly
on the sensor as perpendicular as possible with a minimal angle of
incidence.

When the meter is not in use, please keep the protective cap over the
light sensor. This will prolong the life of the sensor.

When the meter is to be stored for long periods, please remove the
batteries and store them separately. Batteries can leak and cause
damage to the meter’s components.

Avoid areas of high temperature and humidity when using this
instrument.

Maintenance

Battery Replacement

1. Power OFF the meter.

2. Press the button that secures the battery compartment at

the back of the meter while sliding the battery compartment
cover off in a downward motion.

3. Replace the two (2) ‘AAA’ batteries observing correct polarity.

4. Re-assemble the meter before use.

Safety: Please dispose of batteries responsibly; never dispose of
batteries in a fire, batteries may explode or leak. If the meter is not to
be used for 60 days or more, remove the battery and store separately.

Never dispose of used batteries or rechargeable batteries in
household waste.

As consumers, users are legally required to take used batteries
to appropriate collection sites, the retail store where the
batteries were purchased, or wherever batteries are sold.

Disposal: Do not dispose of this instrument in household waste.
The user is obligated to take end-of-life devices to a designated
collection point for the disposal of electrical and electronic
equipment.

Specifications

Display

9999 count LCD

Sampling rate 2.5 times per second

Light sensor

Silicone photodiode with cosine correction
filter

Measurement Units

LUX and FC (Foot candles)

Lighting source
types

Fluorescent, metal halide, high-pressure
sodium, and

incandescent

Input Overload
Display

‘OL’

Tripod mount

On back of meter

Power

2 x 1.5V AAA batteries

Low battery indicator included

Automatic power off

After approx. 12 minutes of inactivity

Operating
Temp/Humidity

5°C to 40°C (40°F to 104°F); <80%RH Max

Operating Altitude

2000 meters (7000ft) maximum

Storage
Temp/Humidity

-10°C to 60°C (14°F to 140°F); <70%RH Max

Dimensions/Weight

133 x 48 x 23mm (5.3 x 1.9 x 0.9”) /250g

(8.8oz)

Safety

For indoor use only. EMC: EN61326-1 (2006),
IEC 61000-

4-2 (2008, IEC 61000-4-3 (2006) + (2007);
Pollution

Degree 2.

Typical Light Levels (1 Fc = 10.76 Lux)

Lux

Foot

Lux

Foot

Candles

Candles

Factories

Home

20-75

2-7

Emergency Stairs,

100-150

10-15

Washing

Warehouse

75-150

7-15

Exit/Entrance
Passages

150-200

15-20

Recreational Activities

150-300

15-30

Packing Work

200-300

20-30

Drawing Room, Table

300-750

30-75

Visual Work:
Production

300-500

30-50

Makeup

Line

750-1,500

75-150

Typesetting:
Inspection

500-1,500

50-150

Reading, Study

Work

1,500-

3,000

150-300

Electronic Assembly,

1,000-

2,000

100-200

Sewing

Drafting

Office

Restaurant

75-100

7-10

Indoor Emergency
Stairs 75-150

7-15

Corridor Stairs

100-200

10-20

Corridor Stairs

150-300

15-30

Entrance,

Wash Room

200-750

20-75

Conference,

300-750

30-75

Cooking Room, Dining
Table

Reception Room

750-1,500

75-150

Clerical Work

750-1,500

75-150

Show Window

1,500-

2,000

150-

2000

Typing, Drafting

Store

Hospital

75-150

7-15

Indoors 30-75

3-7

Emergency Stairs

150-200

15-20

Corridor/Stairs

75-100

7-10

Stairs

200-300

20-30

Reception

100-150

10-15

Sick Room, Warehouse

300-500

30-50

Display Stand

150-200

15-20

Waiting Room

500-750

50-75

Elevator

200-750

20-75

Medical Exam Room

750-1,500

75-150

Show Window,

750-1,500

75-150

Operating Room

Packing Table

1,500-

3,000

150-300

Storefront, Show
Window

5,000­10,000

500-

1000

Eye Inspection

Spectral Sensitivity

Peak sensitivity wavelength: 550nm; Deviation from comparative
luminosity standard: JIS standard C1609-1993.

Warranty

Triplett / Jewell Instruments extends the following warranty to the original purchaser of
these goods for use. Triplett warrants to the original purchaser for use that the products
sold by it will be free from defects in workmanship and material for a period of (1) one
year from the date of purchase. This warranty does not apply to any of our products
which have been repaired or altered by unauthorized persons in any way or purchased
from unauthorized distributors so as, in our sole judgment, to injure their stability or
reliability, or which have been subject to misuse, abuse, misapplication, negligence,
accident or which have had the serial numbers altered, defaced, or removed.
Accessories, including batteries are not covered by this warranty

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